[PATCH 4.9 170/199] blk-mq: make sure that line break can be printed

[Greg Kroah-Hartman]

From: Ming Lei <ming.lei@xxxxxxxxxx>

commit d2c9be89f8ebe7ebcc97676ac40f8dec1cf9b43a upstream.

8962842ca5ab ("blk-mq: avoid sysfs buffer overflow with too many CPU cores")
avoids sysfs buffer overflow, and reserves one character for line break.
However, the last snprintf() doesn't get correct 'size' parameter passed
in, so fixed it.

Fixes: 8962842ca5ab ("blk-mq: avoid sysfs buffer overflow with too many CPU cores")
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Cc: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 block/blk-mq-sysfs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -260,7 +260,7 @@ static ssize_t blk_mq_hw_sysfs_cpus_show
 		pos += ret;
 	}
 
-	ret = snprintf(pos + page, size - pos, "\n");
+	ret = snprintf(pos + page, size + 1 - pos, "\n");
 	return pos + ret;
 }